As a conventional heat process apparatus that performs a heat process for an LCD glass substrate (hereinafter referred to as glass substrate), a direct-contact-type heat process apparatus has been used. In the apparatus, a glass substrate is vacuum-sucked on the upper surface of a heat process board having a heater, a cooling member, or the like. Thus, the lower surface of the glass substrate and the upper surface of the heat process board are contacted. In this state, heat directly transfers from the heat process board to the glass substrate.
In the direct-contract-type heat process apparatus, since heat of the heat process board directly transfers to a glass substrate as a workpiece, the heat transfer efficiency is high. Thus, the glass substrate can be equally heat-processed in a short time.
However, in the direct-contact-type heat process apparatus, friction tends to take place between the glass substrate and the heat process board. The friction causes static electricity to be stored in the glass substrate. When the amount of the static electricity exceeds a predetermined value, a static breakdown takes place. Since the voltage of the static breakdown is as high as several ten kilovolts, it remarkably damages the glass substrate. Thus, the static breakdown is one of major causes that deteriorate the yield of the LCD fabrication. Consequently, it is important to prevent the static breakdown.
As a method for preventing the static breakdown, a non-contact-type heat process method is known. In the non-contact-type heat process method, many small protrusions are disposed on the upper surface of a heat process board. Thus, when a glass substrate is placed on the heat process board, the lower surface of the glass substrate only contacts edge portions of the protrusions. Thus, most portions of the glass substrate are spaced apart from the upper surface of the heat process board. Heat of the heat process board transfers through air in a small space formed between the upper surface of the heat process board and the lower surface of the glass substrate.
In the non-contact-type heat process apparatus, since static electricity due to friction is suppressed, the glass substrate is less damaged by the static breakdown.
However, in the non-contact-type heat process apparatus, since heat indirectly transfers to the glass substrate through air, it takes a time to transfer heat to the glass substrate. In addition, since heat does not equally transfer to the glass substrate, the heat process cannot be equally performed.